1. Field of the Present Invention
The present invention relates generally to the field of bedside patient vital sign monitors, and more particularly to methods and apparatuses for unavoidably recording vital sign data, gathered from a patient by a bedside monitor, in a secure memory device and protecting the data from deletion such that the data may be retrieved and examined by authorized personnel upon the death of the patient or upon the occurrence of another predetermined event.
2. Background
In recent years, the need for information concerning the circumstances surrounding patient injuries, deaths and other medical events has greatly increased. For example, medical research often depends on understanding the connection between the event and a particular biological characteristic, or on the correlation between two or more such characteristics. Ever-increasing medical malpractice litigation demands precise accountability in assessing liability. As a result, considerable effort is expended trying to reconstruct the circumstances around the medical event of interest.
One well-known source of biological information is the bedside monitor or other vital sign sensing device that is connected to many hospital, clinic or even home-care patients. Such devices are frequently used to monitor a patient's basic vital signs, such as respiration, temperature, heart rate and blood pressure; however, they may also be used to monitor a wide variety of other biological information instead of, or in addition to, the more common vital signs. Unfortunately, the information monitored is not typically preserved for later retrieval; if a record of the information is desired, it is typically printed out for preservation. If the monitored information is stored in a memory device at all, it is discarded before any subsequent investigation may take place. As a result, a very important potential source of information is lost.
Monitoring devices that preserve the data they monitor are well known in other environments. For example, flight data recorders, commonly known as black boxes, are found on most large commercial airplanes, and similar recorders are present on many railroad locomotives. However, such black boxes are typically used solely for the purpose of recording data for subsequent retrieval, and are not actually used by the pilot or engineer while operating the airplane or locomotive. In addition, known black boxes are used to monitor operating conditions of a machine, rather than a human, and their operation is thus automatically interconnected to the operation of the machine itself. Moreover, airplanes and locomotives, unlike humans, have no general right to privacy, and thus do not face privacy concerns in the way that human monitoring systems must.
Thus, a need has existed for a patient monitoring system that operates automatically and securely preserves patient vital sign data for future investigation. In particular, a need exists for a black box recorder device that can operate in conjunction with a conventional bedside monitor unit such that the combined system may be easily implemented in hospitals and other healthcare facilities without the need for significant personnel training and that does not significantly raise the price of the monitor unit or the overall system.
All previously-known monitoring devices suffer from one or more drawbacks with regard to their use as a black box, or secure patient data recorder. For example, although there are known to be monitoring devices that include means for recording gathered data, many merely record vital sign data temporarily, until it can be transmitted to a central collection point. Unfortunately, such an approach requires complicated communication procedures, fails to provide any protection for the memory device in the monitor unit, and makes the collected data available to a wide variety of users. For the investigative purposes commonly associated with a black box device, it is generally preferable to simplify the data storage mechanism, protect the integrity of the original memory device itself, and to minimize the accessibility of the device, and the data on the device, to a very small number of analysts. Thus, a need exists for a recorder device that is positioned in the same location as the monitor itself, but that can be readily protected.
Other monitoring and recording devices, such as those disclosed in U.S. Pat. No. 5,701,894 to Cherry et al. and U.S. Pat. No. 5,860,918 to Schradi et al., have means by which the stream of vital sign data gathered thereby is not continuously recorded. If a recorder device is not automatically operated whenever vital sign data is being gathered by the monitor, then its utility as a black box recorder may be easily subverted, and in any event these devices fail to disclose any protective mechanisms for the memory devices themselves.
A few known monitoring devices, such as those disclosed in U.S. Pat. Nos. 5,778,882 and 6,095,985 to Raymond et al. and U.S. Pat. No. 5,687,711 to Halpern et al., provide some software-based protection against unauthorized viewing of recorded vital sign data. Because it is frequently important to protect the confidentiality of patient data, such a function may be important. Unfortunately, the data protection offered by these systems does not protect the data stored on the modules from being overwritten or otherwise erased or corrupted. Thus, a need still exists for a recorder unit that prevents data deletion, and not just data access.
U.S. Pat. No. 6,270,457 to Bardy discloses a system and method of automated collection and analysis of monitored patient data. The data is collected from an implantable device from which the monitored data is periodically uploaded. Unfortunately, the only continuous recordation of which this system is capable is on the device that is implanted inside the patient's body, and such a device is inherently incapable of being used as a black box device.
Thus, a need still exists for a monitor and recorder system that may be placed adjacent a patient such that vital sign data gathered by the monitor device is always automatically recorded in a memory module and protected against accidental or intentional deletion, corruption or replacement except by authorized personnel.